ISO/IEC INTERNATIONAL STANDARD

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1 INTERNATIONAL STANDARD ISO/IEC Sixth edition Information technology Open Systems Interconnection The Directory: Publickey and attribute certificate frameworks Technologies de l'information Interconnexion de systèmes ouverts (OSI) L'annuaire: Cadre général des certificats de clé publique et d'attribut Reference number ISO/IEC :2008(E) ISO/IEC 2008

2 ISO/IEC :2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO/IEC 2008 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel Fax copyright@iso.org Web Published by ISO in 2009 Published in Switzerland ii ISO/IEC 2008 All rights reserved

3 ISO/IEC :2008(E) CONTENTS Foreword... Introduction... SECTION 1 GENERAL Scope Normative references Identical Recommendations International Standards Paired Recommendations International Standards equivalent in technical content Other references Definitions OSI Reference Model security architecture definitions Directory model definitions Access control framework definitions Definitions Abbreviations Conventions Frameworks overview Digital signatures... 9 SECTION 2 PUBLIC-KEY CERTIFICATE FRAMEWORK Public-keys and public-key certificates Generation of key pairs Public-key certificate creation Certificate Validity Repudiation of a digital signing Public-key certificate and CRL extensions Policy handling Key and policy information extensions Subject and issuer information extensions Certification path constraint extensions Basic CRL extensions CRL distribution points and delta-crl extensions Delta CRL relationship to base Certification path processing procedure Path processing inputs Path processing outputs Path processing variables Initialization step Certificate processing PKI directory schema PKI directory object classes and name forms PKI directory attributes PKI directory matching rules SECTION 3 ATTRIBUTE CERTIFICATE FRAMEWORK Attribute Certificates Attribute certificate structure Attribute certificate paths Attribute Authority, SOA and Certification Authority relationship Privilege in attribute certificates Privilege in public-key certificates Page vi vii ISO/IEC 2008 All rights reserved iii

4 ISO/IEC :2008(E) 14 PMI models General model Control model Delegation model Group assignment model Roles model Recognition of Authority Model XML privilege information attribute Permission attribute and matching rule Privilege management certificate extensions Basic privilege management extensions Privilege revocation extensions Source of Authority extensions Role extensions Delegation extensions Recognition of Authority Extensions Privilege path processing procedure Basic processing procedure Role processing procedure Delegation processing procedure PMI directory schema PMI directory object classes PMI Directory attributes PMI general directory matching rules Directory authentication Simple authentication procedure Strong Authentication Access control Protection of Directory operations Annex A Public-Key and Attribute Certificate Frameworks Annex B CRL generation and processing rules B.1 Introduction B.2 Determine parameters for CRLs B.3 Determine CRLs required B.4 Obtain CRLs B.5 Process CRLs Annex C Examples of delta CRL issuance Annex D Privilege policy and privilege attribute definition examples D.1 Introduction D.2 Sample syntaxes D.3 Privilege attribute example Annex E An introduction to public key cryptography Annex F Reference definition of algorithm object identifiers Annex G Examples of use of certification path constraints G.1 Example 1: Use of basic constraints G.2 Example 2: Use of policy mapping and policy constraints G.3 Use of Name Constraints Extension Annex H Guidance on determining for which policies a certification path is valid H.1 Certification path valid for a user-specified policy required H.2 Certification path valid for any policy required H.3 Certification path valid regardless of policy H.4 Certification path valid for a user-specific policy desired, but not required Page iv ISO/IEC 2008 All rights reserved

5 ISO/IEC :2008(E) Page Annex I Key usage certificate extension issues Annex J External ASN.1 modules Annex K Use of Protected Passwords for Bind operations Annex L Alphabetical list of information item definitions Annex M Amendments and corrigenda ISO/IEC 2008 All rights reserved v

6 ISO/IEC :2008(E) Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of the joint technical committee is to prepare International Standards. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. ISO/IEC :2008 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 6, Telecommunications and information exchange between systems, in collaboration with ITU-T. The identical text is published as ITU-T Rec. X.509 (11/2008). This sixth edition cancels and replaces the fifth edition (ISO/IEC :2005), which has been technically revised. ISO/IEC 9594 consists of the following parts, under the general title Information technology Open Systems Interconnection The Directory: Part 1: Overview of concepts, models and services Part 2: Models Part 3: Abstract service definition Part 4: Procedures for distributed operation Part 5: Protocol specifications Part 6: Selected attribute types Part 7: Selected object classes Part 8: Public-key and attribute certificate frameworks Part 9: Replication Part 10: Use of systems management for administration of the Directory vi ISO/IEC 2008 All rights reserved

7 ISO/IEC :2008(E) Introduction This Recommendation International Standard, together with other Recommendations International Standards, has been produced to facilitate the interconnection of information processing systems to provide directory services. A set of such systems, together with the directory information which they hold, can be viewed as an integrated whole, called the Directory. The information held by the Directory, collectively known as the Directory Information Base (DIB), is typically used to facilitate communication between, with or about objects such as application-entities, people, terminals and distribution lists. The Directory plays a significant role in Open Systems Interconnection, whose aim is to allow, with a minimum of technical agreement outside of the interconnection standards themselves, the interconnection of information processing systems: from different manufacturers; under different managements; of different levels of complexity; and of different ages. Many applications have requirements for security to protect against threats to the communication of information. Virtually all security services are dependent upon the identities of the communicating parties being reliably known, i.e., authentication. This Recommendation International Standard defines a framework for public-key certificates. That framework includes specification of data objects used to represent the certificates themselves as well as revocation notices for issued certificates that should no longer be trusted. The public-key certificate framework defined in this Recommendation International Standard, while it defines some critical components of a Public-key Infrastructure (PKI), it does not define a PKI in its entirety. However, this Recommendation International Standard provides the foundation upon which full PKIs and their specifications would be built. Similarly, this Recommendation International Standard defines a framework for attribute certificates. That framework includes specification of data objects used to represent the certificates themselves as well as revocation notices for issued certificates that should no longer be trusted. The attribute certificate framework defined in this Recommendation International Standard, while it defines some critical components of a Privilege Management Infrastructure (PMI), does not define a PMI in its entirety. However, this Recommendation International Standard provides the foundation upon which full PMIs and their specifications would be built. Information objects for holding PKI and PMI objects in the Directory and for comparing presented values with stored values are also defined. This Recommendation International Standard also defines a framework for the provision of authentication services by the Directory to its users. This Recommendation International Standard provides the foundation frameworks upon which industry profiles can be defined by other standards groups and industry forums. Many of the features defined as optional in these frameworks may be mandated for use in certain environments through profiles. This sixth edition technically revises and enhances, but does not replace, the fifth edition of this Recommendation International Standard. Implementations may still claim conformance to the fifth edition. However, at some point, the fifth edition will not be supported (i.e., reported defects will no longer be resolved). It is recommended that implementations conform to this sixth edition as soon as possible. This sixth edition specifies versions 1, 2 and 3 of public-key certificates and versions 1 and 2 of certificate revocation lists. This edition also specifies version 2 of attribute certificates. The extensibility function was added in an earlier edition with version 3 of the public-key certificate and with version 2 of the certificate revocation list and was incorporated into the attribute certificate from its initial inception. This function is specified in clause 7. It is anticipated that any enhancements to this edition can be accommodated using this function and avoid the need to create new versions Annex A, which is an integral part of this Recommendation International Standard, provides the ASN.1 modules which contain all of the definitions associated with the frameworks. Annex B, which is an integral part of this Recommendation International Standard, provides rules for generating and processing Certificate Revocation Lists. Annex C, which is not an integral part of this Recommendation International Standard, provides examples of delta- CRL issuance. ISO/IEC 2008 All rights reserved vii

8 ISO/IEC :2008(E) Annex D, which is not an integral part of this Recommendation International Standard, provides examples of privilege policy syntaxes and privilege attributes. Annex E, which is not an integral part of this Recommendation International Standard, is an introduction to public-key cryptography. Annex F, which is an integral part of this Recommendation International Standard, defines object identifiers assigned to authentication and encryption algorithms, in the absence of a formal register. Annex G, which is not an integral part of this Recommendation International Standard, contains examples of the use of certification path constraints. Annex H, which is not an integral part of this Recommendation International Standard, provides guidance for PKI enabled applications on the processing of certificate policy while in the certificate path validation process. Annex I, which is not an integral part of this Recommendation International Standard, provides guidance on the use of the contentcommitment bit in the keyusage certificate extension. Annex J, which is not an integral part of this Recommendation International Standard, includes extracts of external ASN.1 modules referenced by this Recommendation International Standard. Annex K, which is not an integral part of this Recommendation International Standard, provides a suggested technique for Bind protected password. Annex L, which is not an integral part of this Recommendation International Standard, contains an alphabetical list of information item definitions in this Recommendation International Standard. Annex M, which is not an integral part of this Recommendation International Standard, lists the amendments and defect reports that have been incorporated to form this edition of this Recommendation International Standard. viii ISO/IEC 2008 All rights reserved

9 ISO/IEC :2008 (E) INTERNATIONAL STANDARD ITU-T RECOMMENDATION Information technology Open systems interconnection The Directory: Public-key and attribute certificate frameworks SECTION 1 GENERAL 1 Scope This Recommendation International Standard addresses some of the security requirements in the areas of authentication and other security services through the provision of a set of frameworks upon which full services can be based. Specifically, this Recommendation International Standard defines frameworks for: Public-key certificates; Attribute certificates; Authentication services. The public-key certificate framework defined in this Recommendation International Standard includes definition of the information objects for Public Key Infrastructure (PKI), including public-key certificates, and Certificate Revocation List (CRL). The attribute certificate framework includes definition of the information objects for Privilege Management Infrastructure (PMI), including attribute certificates, and Attribute Certificate Revocation List (ACRL). This Recommendation International Standard also provides the framework for issuing, managing, using and revoking certificates. An extensibility mechanism is included in the defined formats for both certificate types and for all revocation list schemes. This Recommendation International Standard also includes a set of standard extensions for each, which is expected to be generally useful across a number of applications of PKI and PMI. The schema components (including object classes, attribute types and matching rules) for storing PKI and PMI objects in the Directory, are included in this Recommendation International Standard. Other elements of PKI and PMI, beyond these frameworks, such as key and certificate management protocols, operational protocols, additional certificate and CRL extensions are expected to be defined by other standards bodies (e.g., ISO TC 68, IETF, etc.). The authentication scheme defined in this Recommendation International Standard is generic and may be applied to a variety of applications and environments. The Directory makes use of public-key certificates and attribute certificates, and the framework for the Directory's use of these facilities is also defined in this Recommendation International Standard. Public-key technology, including certificates, is used by the Directory to enable strong authentication, signed and/or encrypted operations, and for storage of signed and/or encrypted data in the Directory. Attribute certificates can be used by the Directory to enable rule-based access control. Although the framework for these is provided in this Recommendation International Standard, the full definition of the Directory's use of these frameworks, and the associated services provided by the Directory and its components is supplied in the complete set of X.500 ITU-T series of Recommendation ISO/IEC 9594 (all parts). This Recommendation International Standard, in the Authentication services framework, also: specifies the form of authentication information held by the Directory; describes how authentication information may be obtained from the Directory; states the assumptions made about how authentication information is formed and placed in the Directory; defines three ways in which applications may use this authentication information to perform authentication and describes how other security services may be supported by authentication. This Recommendation International Standard describes two levels of authentication: simple authentication, using a password as a verification of claimed identity; and strong authentication, involving credentials formed using cryptographic techniques. While simple authentication offers some limited protection against unauthorized access, only strong authentication should be used as the basis for providing secure services. It is not intended to establish this as a general framework for authentication, but it can be of general use for applications which consider these techniques adequate. Authentication (and other security services) can only be provided within the context of a defined security policy. It is a matter for users of an application to define their own security policy which may be constrained by the services provided by a standard. ITU-T Rec. X.509 (11/2008) 1

10 ISO/IEC :2008 (E) It is a matter for standards-defining applications which use the authentication framework to specify the protocol exchanges which need to be performed in order to achieve authentication based upon the authentication information obtained from the Directory. The protocol used by applications to obtain credentials from the Directory is the Directory Access Protocol (DAP), specified in ITU-T Rec. X.519 ISO/IEC Normative references The following Recommendations and International Standards contain provisions which, through reference in this text, constitute provisions of this Recommendation International Standard. At the time of publication, the editions indicated were valid. All Recommendations and Standards are subject to revision, and parties to agreements based on this Recommendation International Standard are encouraged to investigate the possibility of applying the most recent edition of the Recommendations and Standards listed below. Members of IEC and ISO maintain registers of currently valid International Standards. The Telecommunication Standardization Bureau of the ITU maintains a list of currently valid ITU-T Recommendations. 2.1 Identical Recommendations International Standards ITU-T Recommendation X.411 (1999) ISO/IEC :2003, Information technology Message Handling Systems (MHS) Message transfer system: Abstract service definition and procedures. ITU-T Recommendation X.500 (2008) ISO/IEC :2008, Information technology Open Systems Interconnection The Directory: Overview of concepts, models and services. ITU-T Recommendation X.501 (2008) ISO/IEC :2008, Information technology Open Systems Interconnection The Directory: Models. ITU-T Recommendation X.511 (2008) ISO/IEC :2008, Information technology Open Systems Interconnection The Directory: Abstract service definition. ITU-T Recommendation X.518 (2008) ISO/IEC :2008, Information technology Open Systems Interconnection The Directory: Procedures for distributed operation. ITU-T Recommendation X.519 (2008) ISO/IEC :2008, Information technology Open Systems Interconnection The Directory: Protocol specifications. ITU-T Recommendation X.520 (2008) ISO/IEC :2008, Information technology Open Systems Interconnection The Directory: Selected attribute types. ITU-T Recommendation X.521 (2008) ISO/IEC :2008, Information technology Open Systems Interconnection The Directory: Selected object classes. ITU-T Recommendation X.525 (2008) ISO/IEC :2008, Information technology Open Systems Interconnection The Directory: Replication. ITU-T Recommendation X.530 (2008) ISO/IEC :2008, Information technology Open Systems Interconnection The Directory: Use of systems management for administration of the Directory. ITU-T Recommendation X.660 (2008) ISO/IEC :2008, Information technology Open Systems Interconnection Procedures for the operation of OSI Registration Authorities: General procedures, and top arcs of the ASN.1 Object Identifier tree. ITU-T Recommendation X.680 (2008) ISO/IEC :2008, Information technology Abstract Syntax Notation One (ASN.1): Specification of basic notation. ITU-T Recommendation X.681 (2008) ISO/IEC :2008, Information technology Abstract Syntax Notation One (ASN.1): Information object specification. ITU-T Recommendation X.682 (2008) ISO/IEC :2008, Information technology Abstract Syntax Notation One (ASN.1): Constraint specification. ITU-T Recommendation X.683 (2008) ISO/IEC :2008, Information technology Abstract Syntax Notation One (ASN.1): Parameterization of ASN.1 specifications. ITU-T Recommendation X.690 (2008) ISO/IEC :2008, Information technology ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER). ITU-T Recommendation X.691 (2008) ISO/IEC :2008, Information technology ASN.1 encoding rules: Specification of Packed Encoding Rules (PER). 2 ITU-T Rec. X.509 (11/2008)

11 ISO/IEC :2008 (E) ITU-T Recommendation X.812 (1995) ISO/IEC :1996, Information technology Open Systems Interconnection Security frameworks for open systems: Access control framework. ITU-T Recommendation X.813 (1996) ISO/IEC :1997, Information technology Open Systems Interconnection Security frameworks for open systems: Non-repudiation framework. 2.2 Paired Recommendations International Standards equivalent in technical content CCITT Recommendation X.800 (1991), Security Architecture for Open Systems Interconnection for CCITT applications. ISO :1989, Information processing systems Open Systems Interconnection Basic Reference Model Part 2: Security Architecture. 2.3 Other references IETF RFC 5280 (2008), Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile. ITU-T Rec. X.509 (11/2008) 3